Different azimuths in parallel?

[Karanx7]

I got my full plan set, and I have south facing panels and east facing panels. It looks like they ran the south facing panels in parallel with half of the east panels, and left the other half of the east panels on their own string. Why would they do this? Wouldn't it be better to have the east facing panels in parallel, and the south panels on their own MPPT?

Here's the roof layout:

Here's the design:

 

[power.saver]

I got my full plan set, and I have south facing panels and east facing panels. It looks like they ran the south facing panels in parallel with half of the east panels, and left the other half of the east panels on their own string. Why would they do this? Wouldn't it be better to have the east facing panels in parallel, and the south panels on their own MPPT?

Here's the roof layout:
View attachment 1011513

Here's the design:
View attachment 1011514

The east facing roof MP1 has an odd number of panels (19) and can't be paralleled with itself. Parallel strings need the same number of panels. So they used 10 from MP2 with 10 from MP1, and the remaining 9 on MP1 in its own string.

If you could add one more panel to MP1 then it would be two strings of 10, plus the MP2 string by itself.

 

[Karanx7]

Wouldn't running strings on different azimuths be inefficient if one string is shaded? Would it be better to remove one panel, and have the east side be 18 panels, with 9 running in parallel with 9? The current setup is 11.745kw, so I can't add another panel without becoming a Florida Tier 2 system.

 

[power.saver]

Wouldn't running strings on different azimuths be inefficient if one string is shaded? Would it be better to remove one panel, and have the east side be 18 panels, with 9 running in parallel with 9? The current setup is 11.745kw, so I can't add another panel without becoming a Florida Tier 2 system.

Yes, you could remove a panel so the MP1 has an even number (18) and then split them into two parallel strings.

You might ask your advisor if the PW 3 supports 3 MPPT strings, in which case you don't have to parallel anything and can stay with 29 panels of three strings (10+10+9). I don't know how many MPPTs there are in the PW 3, as I have an older system that doesn't use them.

 

[yblaser]

According to the spec sheet the PW3 has 6 MPPT inputs, so the best solution would be not to parallel any of the strings, but for some reason Tesla likes to design systems this way.

BTW having two strings in parallel is inefficient if there is non uniform shading between the two strings regardless if they are on the same azimuth or not.

 

[CrazyRabbit]

Tell them NO (10 panels south on one string), and not to parallel home runs on east array as they will be not equal qty of panels (nine and ten).